What affects Interstial Fluid?

I just saw in another thread the mention of dehydration and its effect on interstitial fluid. I’m curious if anyone knows of anything else that could have an effect?

I’m asking because I use my calibration factor to help guide decisions throughout my day. I calculate it using my current BG and the ISig that I get from my Medtronic Guardian. Up until about 6 weeks ago, this number was critical in helping me to avoid the swings, but something has changed, and I’ve been having a hard time learning its patterns again.

Generally speaking, I usually have a range between 2-7 or 8, but my range for the last many weeks has gone up to 5-12. This is an enormous jump for me, and I’m not sure how to use the numbers. Interestingly, this jump in range has not seemed to have affected the Sensor’s accuracy (still consistently inaccurate at best) except to make calibrating difficult.

I am trying to figure out what could’ve changed since I started studying this almost 8 months ago. I thought it was the batch of sensors, thought it was the transmitter. All have been replaced. Now I’m wondering about something more internal… could inflammation affect interstitial fluid? Or what about a change in diet??

You guys might not have any idea. I obviously don’t. But, as usual, if you have any thoughts AT ALL, I sure would like to hear them…

On the simplest level, overhydration can also affect interstitial fluid, but whether the effect parallels that of dehydration when it comes to sensor reliability, I don’t know. Are you drinking more because the weather is warmer and/or you’re exercising more?


What an interesting idea… I’d hardly call what I’m doing “overhydration”, BUT there has been a change in the amount of water I’m drinking. I’m usually terrible about water, but I’ve been making myself drink about 32 oz a day. Is there a chance that change could account for it??

Hydration also affects my insulin sensitivity. I’m not really sure if that could be a factor here.

Are you saying the calibration factor range changed? How do you use the calibration factor? I’m not that familiar with the guardian.

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Yes, my general range has changed. Since the beginning of tracking this thing, I’ve learned patterns… they are predictable and very useful. Basically all sensors use an ISIG (or something like it?) in order to get a value from the interstitial fluid. Medtronic is different because they make theirs visible. Which is incredible. So the sensor will use your ISIG, based on the last calibration, to produce a sensor value. This is a predicted value that it calculates after doing everything else it does with noise, distortion… I don’t know about these things. However, the ISIG is the raw number. So I use it with a current BG to calculate a calibration factor, and this factor shows me BASICALLY where I am in the process of the glucose-IF push and pull (I can’t say for sure that’s what’s happening because that’s only one theory—the push and pull— but it’s an easy way to say it). Either way, I can get this number that gives me more information than just a BG alone, and it’s been great for guidance. Up until about 6 weeks ago, my range has always been 2.3 (it’s never been lower)-11. Those were my extremes. But almost EVERYTHING fell within about a 3.5-8… and an 8 wa really a high one. Now there’s been some kind of shift and even during EXERCISE, I will see an 8 or 9. It makes NO sense to me, and I’m back to being on this stupid roller coaster. I wasn’t sure where else to go as I haven’t done enough reading in this area, as I hadn’t needed to yet, so I figured I’d ask here. They have special powers here, and there was a chance they’d have the answer. However, I’m prepared to get to reading… Hopefully I’ll get something from that.

That’s interesting about hydration and insulin sensitivity, too. I had never thought of that either…

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That is interesting! Perhaps someone else will have some good ideas. I had no idea that factor was available on the Guardian. I’m not really sure how I would use it, but it is interesting.

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This might be obvious, but I will mention it just in case people are not totally sure.

Anything (almost) can count toward hydration and the daily total ounces that you drank, not just water.

Water is generally considered the best thing for general health, but you can count anything for total fluid volume for your hydration numbers.

(except rum, sorry Nicky :stuck_out_tongue_winking_eye:)


And here I thought I was blinding you with insightful and intuitive thinking and with overall highly intelligent remarks… and you think I’ve been drinking. :smiley:

Yes, I do know that’s how it works, but there’s no end to the guilt anyway. Water is magic. It’s found throughout the universe. It surely should be good enough for me. But the majority of my liquids, despite possible beliefs around here to the contrary, come in the form of coffee, coke zero :frowning: and bottles of water… spiked with chemical and dye. Let’s stop talking about my liquid intake now. This doesn’t feel good.

I’m drinking almost 32 ounces of water a DAY, dammit. Just let me put that out there and be proud (and overly concerned with the effect it’s having on my life in case I need justification if it goes back to 0)…

Shouldn’t you be at work?

Oh! Quick question while you’re here… I’ve got 0 IOB, flat as can be, BG of 100, and about to start my 0 Basal… I was looking at your carb chart for starting BGs, and speaking of coffee, can i skip the carbs and have a coffee before going out?? If i can promise you it will spike me?? :pray: I can’t be sure I can survive a run without coffee…


You can try the coffee. Although not yet scientifically proven, there is a very well-accepted belief in the running community that caffeine helps shift your metabolism toward using more fat for fuel, instead of blood glucose and muscle glycogen. That is why some people use gels that have caffeine in them.

So sure, try it!

But just check the BG a few times before you start.

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Which is EXACTLY what I was thinking… so I’m glad you’d heard that, too. :grin:

You just made my day. :hugs:

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So if I know it’s going to raise my BG, when should I head out? Before it rises? Or once it’s begun??

If you are sure it will raise you, drink it and hit the pavement!

But last time, you plummeted, so keep that in mind too…




thank god. i love Diet Pepsi :wink:

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